WO 2012/027542 A2 discloses a microscope that simultaneously permits both optical tomographic investigation and SPIM investigation of a sample. This document concretely recites optical projection tomography (OPT). Disadvantageously, the microscope is of very complex construction; in particular, three objectives precisely aligned with one another are required simultaneously in order to focus illuminating light onto the sample and to receive detected light, emerging from the sample, for the respective detectors. The microscope moreover is not flexibly usable. For example, the sample must obligatorily be moved relative to the microscope so that three-dimensional images of the sample can be generated; this is cumbersome and not possible with every type of sample, since the experimentation space is restricted by the three objectives. Implementation of such a microscope in a conventional microscope configuration, in particular using a conventional microscope stand, is moreover not possible or at best possible only with difficulty, making the manufacture of such a microscope complex and costly.